Remove Chrome OS-related GN build configuration

build/config/sysroot.gni

Index: build/config/sysroot.gni
diff --git a/build/config/sysroot.gni b/build/config/sysroot.gni
index 2be55c8fa5a5908e6a1bc13c5355d26b3d4dc868..4fcfc4b323e5300342f7a0c34db978149834efeb 100644
--- a/build/config/sysroot.gni
+++ b/build/config/sysroot.gni
@@ -34,7 +34,7 @@ if (current_toolchain == default_toolchain && target_sysroot != "") {
   }
 } else if (is_fnl) {
   assert(false, "FNL needs target_sysroot")
-} else if (is_linux && is_chrome_branded && is_official_build && !is_chromeos) {
+} else if (is_linux && is_chrome_branded && is_official_build) {
   # For official builds, use the sysroot checked into the internal source repo
   # so that the builds work on older versions of Linux.
   if (current_cpu == "x64") {
@@ -46,7 +46,7 @@ if (current_toolchain == default_toolchain && target_sysroot != "") {
     # Any other builds don't use a sysroot.
     sysroot = ""
   }
-} else if (is_linux && !is_chromeos) {
+} else if (is_linux) {
   if (current_cpu == "mipsel") {
     sysroot = rebase_path("//mipsel-sysroot/sysroot")
   } else {